drm/i915: Stop hand rolling drm_crtc_mask()

Use drm_crtc_mask() instead of hand rolling it.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210609085632.22026-2-ville.syrjala@linux.intel.com


Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>